Glaciodynamic sequence stratigraphy
Published:January 01, 2012
Stig A. Schack Pedersen, 2012. "Glaciodynamic sequence stratigraphy", Glaciogenic Reservoirs and Hydrocarbon Systems, M. Huuse, J. Redfern, D. P. Le Heron, R. J. Dixon, A. Moscariello, J. Craig
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The glaciofluvial deposits are by volume and permeability the most important unit in the terrestrial glacial successions, and they are the obvious target for groundwater as well as hydrocarbon reservoir exploration. The dominant glaciofluvial units are related to the proglacial setting in the foreland of an advancing ice margin, which results in a coarsening-upwards sequence with fine-grained beds at the base and glaciofluvial gravel at the top. In a complete sequence a till caps the unit, and at its base a glacitectonite is formed by shearing related to the development of the deformational layer below the ice. The glacial deposits laid down during the same glacial advance represent a glaciodynamic sequence. An important feature added to this is the proglacial glaciotectonic deformation. The glaciotectonic architectural elements comprise thrust faulting, folding of hanging-wall anticlines, thrust-sheet duplexes, hydrodynamic breccias and mud diapirs, the structural style of which define the glaciotectonic complex. The glaciodynamic sequence corresponds to the glaciodynamic event related to one major ice advance. The glaciodynamic processes representing the event comprise deposition as well as deformation, creating a glaciogenic sedimentary succession and a set of glaciotectonic structures. These constitute the elements to be recognized for defining a glaciodynamic sequence.
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Glaciogenic Reservoirs and Hydrocarbon Systems
Glaciogenic reservoirs and hydrocarbon systems occur intermittently throughout the stratigraphic record, with particular prominence in Neoproterozoic, Late Ordovician, Permo-Carboniferous and Late Cenozoic strata. Recent interest in glaciogenic successions has been fuelled by hydrocarbon discoveries in ancient glaciogenic reservoirs in North Africa, the Middle East, Australia and South America. Glaciogenic deposits of Pleistocene age are noteworthy for their content of groundwater onshore and potentially prospective and/or hazardous gas accumulations offshore. The abundant imprints of Pleistocene glaciations in both hemispheres can be used to reconstruct complex histories of repeated ice cover and retreat, and glacier-bed interactions, thus informing our view on the dynamics of older ice caps and predictions of future glaciations. This volume aims to provide a better understanding of glaciogenic processes, their stratigraphic record and reservoir characteristics of glaciogenic deposits. The book comprises 3 overview papers and 16 original case studies of Neoproterozoic to Pleistocene successions on 6 continents and will be of interest to sedimentologists, glaciologists, geophysicists, hydrologists and petroleum geologists alike.